would this make a good copper heatsink??

[jordyyy]

1 lb copper bar. 1 pound copper bullion. .999 fine - eBay (item 180526683194 end time Sep-26-10 18:23:24 PDT)

1lb copper block?
this also have 8oz ones...

Would these make good heatsinks for lm3875 dual mono? I noticed Peter Daniels likes to use copper blocks on his amps, and these seem pretty cheap. Any thoughts?

[sq225917]

They will sure look sweet. No reason why not to use them.

[Groundloops]

Did it before with similar copper blocks. It just works, but aside of looking fancy there is no benefit.

[Luke]

Originally Posted by Groundloops

Did it before with similar copper blocks. It just works, but aside of looking fancy there is no benefit.

Did you compare the sound to aluminum

[wwenze]

1 pound of copper bar is pretty small for an unfinned block for heatsink though.

I remember seeing full-copper finned fanned heatsinks weighing 1kg for computer use.

[AndrewT]

your 1lb of copper is about 3.5cub in.
Looking at the pic, I'll guess that the copper block is ~2.5in long.

@$6.5 +4.5post that 1lb block is costing you >$24,000.00 per tonne

[SRMcGee]

jordyyy:

I've built 4 LM3875 Gainclones, each with a 5" * 2.5" * 0.75" copper heatsink. The copper blocks work well but are a royal pain to drill; you gotta go verrry slowly or you'll break your bits.

Regards,
Scott

[Andy5112405]

Copper will make NO DIFFERENCE to the sound AT ALL. It is purely the temperature of the output devices that is of concern.

Try to keep them below 60 Degrees C for reliability. Some people say 80 Degrees C is OK but electrolytics start to dry out pretty quickly under elevated temperatures.

With all heatsinks you are after surface area so a block will have nothing like the surface area of a finned heatsink. If you can saw a few channels into the block to make it into a conventional heatsink topography then you are talking. Copper is a better conductor of heat than alluminium.

[Andrew Eckhardt]

If you want to get what copper has to offer you have to focus on what that is. Copper has higher thermal conductivity but much lower thermal mass. In other words, copper is great in a well calculated amount for immediately spreading heat from a small area to a larger one so that the resistance of the Second interface can be made less significant. A the package you're still limited by the area of the thermal pad, and to get absolute maximum thermal performance you should already be exploring things like electrically non-insulated connections from package to sink, otherwise the copper probably wont do much of anything. Copper is great for very small heatsinks where high thermal mass is impossible anyway. A sink with lots of aluminum in it will stay at the same temperature for longer than one made entirely of copper, increasing thermal stability over the copper sink no matter what is the average temp of the sink or ambient air.

[kavermei]

Also, you would do well to paint the copper matte black (except where the transistors are mounted), this will significantly improve heat radiation.